Hey there jpstereo,
I myself wondered that same thing when I was heavily researching DAC/Amp combos. I think the D1 may be considered a bit more "portable", putting it in another category, but compared to others, it's still not that small.
The Fubar products certainly look nice. Well constructed and a reputable company AFAIK. I think, as with all forums of this type, there is a type of "pack mentality" (for lack of a better term) that makes certain products extremely popular for awhile. During that time, they overshadow many other perfectly good products. After a bit of time has passed, you'll start to see some D1's FS I think. I know there's a cute term for this phenomenon, but I can't think of it right now.
BTW, I ended up going with a simple SuperPro DAC707. It was really cheap, yet has pretty good internals for the price. I already had a serviceable amp, so all I really needed was a DAC.